[SCG66-P14] Developing efficient methods to collect and observe microfossils of fish teeth (ichthyoliths) from pelagic clay for determining depositional ages of pelagic clay
Keywords:pelagic clay, age determination, microfossils, ichthyolith, deep learning, object detection
It has long been recognized that determining depositional ages of pelagic clay is a challenge, because age-diagnostic calcareous/siliceous microfossils are seldom contained and paleomagnetic records are often ambiguous. Our studies [2,3] have shown that biostratigraphy of ‘ichthyoliths’ (microfossils of fish teeth and denticles [e.g. 4]) provide key constraints on depositional age of pelagic clay. However, traditional methods for collection and observations of ichthyoliths were troublesome; ichthyoliths were concentrated from samples by sieving and then manually picked from sieved samples to slide glasses under stereomicroscope. Therefore, observing enough amount of ichthyoliths from various samples is time consuming.
To overcome the problem, we first constructed a new method to concentrate a lot of ichthyoliths in a short time. We found that a combination of elutriation and heavy-liquid separation effectively accumulates ichthyoliths from pelagic clay. We then developed a method for direct detection of ichthyoliths by utilizing a slide scanner and deep learning-based technologies called ‘Mask R-CNN’ . We are now improving the accuracy of the model. The latest results will be shown in the presentation.
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